I have a game loop like this: #The velocity of the object velocity_x = 0.09 velocity_y = 0.03 #If the location of the object is over 5, bounce off. if loc_x > 5: velocity_x = (velocity_x * -1) if loc_y > 5: velocity_y = (velocity_y * -1) #Every frame set the object's position to the old position plus the velocity obj.setPosition([(loc_x + velocity_x),(loc_y + velocity_y),0]) Basically, my problem is that in the if loops, I change the variable from its original value to the inverse of its old value. But because I declare the variable's value at the beginning of the script, the velocity variables don't stay on what I change it to. I need a way to change the variable's value permanently. Thank you!